1. Field of the Invention
This invention relates to a method and apparatus for rotating a throttle blade on a throttle shaft between maximum and minimum airflow positions. Specifically, at least a portion of a drive assembly is mounted within the throttle blade to move the blade between various airflow positions.
2. Related Art
Throttle valves typically include a throttle blade or disc attached to a throttle shaft, which extends across a bore formed in a throttle body. The throttle blade rotates within the bore to control air flow from an intake manifold to a vehicle engine. A pair of bearings is supported by the throttle body to facilitate rotation of the throttle shaft.
A mechanical linkage or motor and geardrive are typically mounted to one side of the throttle body to provide the power necessary to rotate the throttle blade within the throttle body. In embodiments with a motor, a position sensor is mounted to the throttle body to monitor the position of the shaft within the bore. Multiple assembly operations are required to assemble the various components. The bearings are installed within the throttle body, the shaft is assembled into the throttle body, the blade is mounted to the shaft, the motor and geardrive or mechanical linkage are mounted to the body, and the position sensor is mounted to the body. This assembly process is labor intensive and time consuming.
Another disadvantage with this assembly process is that mounting the position sensor, motor, and geardrive on the throttle body takes up valuable packaging space. Thus, it is desirable to provide an improved drive mechanism and position sensor in a more modular form that is easy to install, and which overcomes the deficiencies with prior art systems.
The subject invention provides a drive assembly that is at least partially mounted within a throttle blade for controlling the rotational movement of the blade within a throttle body. A position sensor preferably is also provided to monitor the position of the blade relative to the throttle body. The mounting of at least a portion of the drive assembly within the blade eliminates the need to provide separate exterior mounting of such components on the throttle body. This provides a more modular design that decreases assembly time and cost.
In a disclosed embodiment of this invention, a throttle assembly includes a throttle body with an airflow passage defining a longitudinal axis and having a bore intersecting the airflow passage. The bore defines an axis of rotation that is transverse to the longitudinal axis. A throttle blade is mounted for rotation about the axis of rotation defined by the bore. The blade rotates within the airflow passage between a maximum airflow position and a minimum airflow position. A drive mechanism is supported within the throttle blade to move the blade between the maximum and minimum airflow positions.
In a preferred embodiment, the blade has a central bore that houses the drive mechanism. A position sensor can optionally be mounted within the bore to monitor the position of the blade and for generating a signal representing the blade position that can be utilized by an electronic throttle control system.
The inventive method for driving the throttle blade between maximum and minimum airflow positions includes the following steps. The throttle body is provided with an airflow passage defining a longitudinal axis and a rotation axis intersecting the airflow passage. A throttle blade is mounted for rotation about the axis of rotation. A drive mechanism is secured to the throttle blade and the blade is driven between the maximum and minimum airflow positions by the drive mechanism. Additional steps include forming a central bore within the blade and installing the drive mechanism within the bore and mounting a position sensor within the bore to monitor the position of the blade relative to the throttle body.
These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.